Mercedes have confirmed that Williams driver George Russell has been drafted in to replace Lewis Hamilton at this weekend's Sakhir Grand Prix.
The reigning world champion was ruled out of the race after receiving a positive test for coronavirus on Monday, one day after taking victory in the most recent race.
"George has been released by our partner team Williams Racing in order to join Mercedes this weekend in Bahrain," the team said in a statement.
"First and foremost, I wish to thank our loyal partners at Williams for their collaboration and open-mindedness in making it possible for George to race for Mercedes this weekend," said team principal Toto Wolff.
"The conversations with the team at Williams were positive and pragmatic, and those were the key factors in reaching an agreement.
"It will not be a straightforward task for George to make the transition from the Williams to the W11, but he is race-ready and has detailed understanding of the 2020 tyres and how they perform on this generation of cars.
"George has shown impressive form this year with Williams, playing an instrumental role in their climb up the grid," he continued.
"I am optimistic that he will deliver a strong performance alongside Valtteri [Bottas], who will be a demanding reference for him.
"We have a job to do this weekend, and the full focus of our sporting efforts will be behind Valtteri and George in order to maximise our points score as a team.
"But, of course, our thoughts are also with Lewis, and we will be supporting him as much as we can to make a rapid recovery during his period of self-isolation."
Russell has been a member of the Mercedes-Benz Junior Programme since 2017, when he won the GP3 Series championship as a rookie.
He went on to capture the Formula 2 title in 2018, leading to his F1 debut in 2019 with Williams.
With his debut for the team this weekend, Russell becomes only the fifth driver to compete for Mercedes since it return to F1 in 2010 with a line-up cnsisting of Michael Schumacher and Nico Rosberg.
"This race will mark a small milestone for us, as we see a member of our Junior programme compete for the works Mercedes team for the first time," acknowledged Wolff.
Meanwhile Williams has announced that reserve driver and current F2 competitor Jack Aitken will step in for Russell.
It's not yet known whether Hamilton will be able to get back in the car in time for the final race of the season at Abu Dhabi the following weekend.